Teens Are Leaving Facebook And This is Where They Are Going

Solis also mentioned AskFM as a popular teen hangout. This social network allows users to pose questions to one another and is similar in design to Reddit threads. According to Business Insider, half of the network's 65 million users are under 18. But because of the anonymity of users, teens are said to be particularly harsh and mean.

And then, of course, there is Twitter. According to Piper Jaffray's semi-annual teen market research report, Twitter overtook Facebook in terms of popularity with teens. Twenty six percent named Twitter as their "most important" social site, while only 23 percent said Facebook was most important, down from 42 percent the year before.

As Facebook is learning, with teens what's in one day is out the next.